Ever changing exchange rates could make producing product more or less expensive, which could also cause the prices or products to also fluctuate.
Shortly after the UK's Brexit announcment the pound fell dramactically, the most it has done in 30 years (at the time of me writing this sterling had continuted to fall to $1.239 compared with $1.50 right before the result was announced) This could either cause a raise in prices for customers or brands could take on this extra cost, meaning less profit.
These has been an increase in tourists due to the fallen pound as they enjoy a favourable exchange, this has also made coming to the UK around 20% cheaper comapred to last year, making it the go-to location. Most recently China has been celebrating their week long holiday called 'China's golden week' which saw many chinses tourists holidaying around the world and shopping.
Economic